gsutil: upgrade to 4.7

This is what newer depot_tools expects.

BUG=chromium:452497
TEST=precq bots pass

Change-Id: Ie23f9a15f0c9ada2facc141bcbd092e7dfbdea9f
Reviewed-on: https://chromium-review.googlesource.com/243049
Trybot-Ready: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Shawn N <shawnn@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
29 files changed